Microscopic pest causes serious garden damage

Oct. 5, 2013

Written by

Jeff Ishee

One of the most difficult garden pests to control, especially in annual vegetable crops, is the root-knot nematode. Nematodes are microscopic eel-like roundworms that feed on plant roots, restricting a plants ability to take up water and nutrients. The adults are tiny, making them very difficult to detect visually. Symptoms of root-know nematode damage include stunted or discolored plants. Vegetables might also wilt more than usual in hot, dry weather.

Root-knot nematodes attack a wide range of food crops, including sweet corn, beans, cabbage, lettuce, potatoes, tomatoes and squash. The average home vegetable gardener is not even aware of what may be causing the problem  until they pull a plant out and notice distinctive galls on the roots.

Home gardeners, unlike commercial farmers, have limited access to chemicals to control nematodes. Because of the extremely high toxicity level of nematicides, most home gardeners would not choose these chemicals for home use. Therefore, gardeners should know how to control nematodes using a variety of techniques.

 Plant vegetable varieties that are nematode resistant. When choosing seed varieties, look for letters on the package such as VFN. The letter N indicates resistance to nematodes. Lemon Boy and Celebrity are examples of tomatoes with nematode resistance.

 Sow non-host plants such as annual rye and winter wheat in rotation with garden vegetables. This breaks the life cycle of nematodes.

 When plants are removed in late summer, till the soil and cover with clear plastic sheeting and leave in place for at least four weeks. Soil solarization is a good method of temporarily reducing nematode populations in the top 6 inches of soil. Nematodes, including egg stages, are killed when soil temperatures exceed 125 degrees.

 Destroy roots of vegetable plants as soon as they are no longer wanted or productive in the garden. Nematodes continue to feed and reproduce on root fragments in the soil and build up for the next crop season.

 Consider relocating the garden. Moving the garden, however, to a new site does not ensure freedom from nematodes. They can survive and thrive on the roots of certain farm crops as well as weeds and woody plants.

Gardeners can almost never completely eliminate nematodes. This means taking various steps to control this pest each year.